Activity of soil drenching and foliar insecticide applications on flea beetles (Chrysomelidae) in cabbage and eggplant transplants

Flea beetles (FB), Epitrix spp. and Phyllotreta spp., are important economic pests of a wide variety of vegetable crops in North America including eggplant and cabbage. In response to some recent inquiries as to whether certain insecticides and application methods are efficacious for FB control, we conducted a field efficacy experiment at three locations (Whitethorne, VA, Painter, VA, and Mills River, NC) and on both eggplant and cabbage in 2015. Four different chemicals were tested, the neonicotinoids imidacloprid and dinotefuran, the diamide cyantraniliprole, and the pyrethroid bifenthrin. All were applied in both a transplant soil drench and a foliar spray to both eggplant and cabbage with the exception of bifenthrin, which was applied as foliar spray only. FB density and defoliation was assessed weekly for about one month after application.   Crop yield was also assessed on eggplant and cabbage in Whitethorne. The predominant FB species on eggplant was Epitrix fuscula and on cabbage were Phyllotreta striolata and P. cruciferae. At Whitethorne and Painter, all insecticide treatments provided effective control of FB up to one wk after application. Insecticide treatments were less effective at Mills River.  In general, dinotefuran applied as a transplant soil drench provided the most effective FB control, having the fewest number of FBs, the lowest percent defoliation, and the longest lasting control. As a whole, only the soil drench application of dinotefuran provided effective control.  Among the foliar spray applications, bifenthrin provided more consistent effective FB control than the other insecticides in both eggplant and cabbage.